PV Hybridisation Model — Evaluate Co-located BESS on an Existing Solar PV Plant Across 8 Markets

Description
If you develop, advise on or finance battery co-location on existing solar PV plants, you know the problem: the financial question is not whether a standalone BESS is viable, but whether adding a BESS to a specific existing PV plant creates incremental value over leaving the plant as it is. The answer depends on the connection constraint — how much of the authorised grid capacity is already occupied by the solar plant during peak hours — and on how the existing FV incentive regime interacts with the new BESS asset. No standalone BESS model answers this correctly because it does not start from the FV baseline.
This model does.

Open it, enter the existing PV plant data — capacity, year of commission, current production, connection capacity and incentive regime — then size your BESS and allocate revenue streams. The model runs the FV as-is baseline and the FV+BESS hybrid in parallel, shows the incremental NPV the BESS adds, and calculates the BESS incremental IRR against the capital deployed on battery storage alone. All from a single control panel.


What makes it different from a standalone BESS model
The connection constraint engine is the core differentiator. The model starts from the key physical reality of hybridisation: the BESS must discharge through the existing FV grid connection, and during hours when solar production is at or near the connection capacity limit, the BESS cannot discharge at all. A 20% capacity derating is applied to all BESS revenues to account for this constraint, reflecting the fact that peak solar hours — when the connection is most congested — are also the hours when arbitrage spreads are most valuable. For site-specific analysis, the derating factor is fully user-configurable. This constraint is what makes hybridisation financially different from a greenfield co-located BESS, and models that ignore it systematically overstate the return.

The FV baseline engine runs a full 20-year degradation projection of the existing plant — at 0.45-0.50%/year depending on country — producing the correct As-is cash flow including residual incentive revenue until expiry and then market revenue, with OPEX escalation at 2.5%/year. The BESS incremental IRR is calculated against this baseline, not against zero, which is the only economically correct way to evaluate the co-location decision.

The BESS revenue engine covers four streams: Arbitrage, Ancillary Services and Capacity Market, each with country-specific benchmarks, plus a 5% revenue haircut applied across all streams. Country-specific market activation mirrors the BESS Ultimate Model — Capacity Market is active where the market exists and disabled elsewhere. BESS cycle degradation at 0.5%/year is applied to effective capacity across the 20-year horizon.

The incentive interaction module handles the key regulatory question: does adding a BESS affect the existing FV incentive? The model correctly reflects the answer for each market. In Italy under D.L. 21/2026, all five CE options are available — As-is FV plus new BESS preserves the full CE tariff; Repowering with Quota A/B allows the BESS to arbitrage both CE and market hours; the exit indemnity in Mode 5 can partially fund BESS CAPEX. In Germany, BESS co-location preserves the EEG tariff on FV production, with the battery earning market revenues independently. In the UK, BESS addition does not affect ROC certificate status. In the USA, the ITC credit applies to the BESS CAPEX as a standalone qualifying asset.

The financing module structures the BESS debt separately from the existing FV plant — a 12-year tenor on the BESS with country-specific rates — producing a standalone BESS DSCR alongside the combined FV+BESS project metrics.


Who this is for
Developers and asset managers evaluating BESS co-location on existing solar PV plants where the connection capacity is a binding constraint on BESS dispatch. Financial advisors preparing business cases for hybridisation investment where the incremental return on BESS capital needs to be demonstrated separately from the FV plant returns. Infrastructure investors reviewing portfolio assets for hybridisation upside, particularly in Italy where D.L. 21/2026 creates five distinct regulatory paths that interact differently with the co-location decision.


Workbook: Cover · CONTROL_PANEL · PV_INPUTS · BESS_INPUTS · INCENTIVE_CONFIG · BASELINE_ENGINE · HYBRID_ENGINE · COMPARISON_ENGINE · FINANCIAL_MODEL · DASHBOARD.


For custom versions, country extensions or specific requests, contact us at [email protected]